High voltage isolation communication devices known in the prior art include optical devices, magnetic devices and capacitive devices. Prior art optical devices typically achieve high voltage isolation by employing LEDs and corresponding photodiodes to transmit and receive light signals, usually require high power levels, and suffer from operational and design constraints when multiple communication channels are required.
Prior art magnetic devices typically achieve high voltage isolation by employing opposing inductively-coupled coils, usually require high power levels (especially when high data rates are required), typically require the use of at least three separate integrated circuits or chips, and often are susceptible to electromagnetic interference (“EMI”).
Prior art capacitive devices achieve voltage isolation by employing multiple pairs of transmitting and receiving electrodes, where for example a first pair of electrodes is employed to transmit and receive data, and a second pair of electrodes is employed to refresh or maintain the transmitted signals. Such capacitive devices typically exhibit poor high voltage hold-off or breakdown characteristics
The design of small high speed galvanic isolators or coil transducers presents several formidable technical challenges, such as how to handle EMI, large-magnitude fast transients, and other forms of electrical noise while maintaining high voltage breakdown characteristics, and acceptable data or power transfer rates.
In some electrical circuits, logic signals are transmitted between two locations that must be kept electrically isolated from each other. For example, high voltages in medical test equipment must be kept separated from patients, and factory operators must be kept safe when operating high-voltage and/or high-current machinery. An isolator can be employed to separate a control circuit from a high-voltage and/or high-current circuit, where the control circuit is actuated by an operator, thereby protecting the operator. In addition, the control circuit itself must be isolated adequately from the high voltages and/or currents of the high-voltage and/or high-current circuit. In some types of isolators, however, signal transmission can be disrupted in environments containing considerable amounts of EMI. To provide reliable signal transmission, an isolator should be designed to reject or reduce EMI. What is needed are means and methods to minimize the susceptibility of small high speed galvanic isolators to EMI.